1. Field of the Invention
The present invention relates to an optical pickup for an optical disk drive, and more particularly, to an optical pickup for adjusting a distance between the optical disk and an object lens and for recording or reproducing data on or from an optical disk maintaining stability from external shock or collision while being floated toward an optical disk by an air bearing.
2. Description of the Related Art
Generally, an optical disk player records or reproduces the data on or from an optical disk such as a CD, CD-ROM, DVD, DVD-ROM, etc. The optical disk player comprises an optical pickup for recording or reproducing the data by focusing a light on the recording surface of the optical disk.
The optical pickup generally includes an object lens for focusing the light on the optical disk, a bobbin for supporting the object lens, a wire spring for movably supporting the bobbin with respect to a base and a driving unit moving the bobbin. Here, the driving unit includes a focusing coil wound around the bobbin for driving the bobbin in a focusing direction of the light, tracking coils for driving the bobbin in a tracking direction, that is, in a diameter direction of the optical disk, and magnets disposed to correspond to the focusing and tracking coils.
In the above conventional construction, the position of an optical head section including the object lens is determined by driving the respective coils. Namely, the optical head is adjustably positioned in the direction toward or away from the optical disk by the electromagnetic force generated when applying the electric current to the focusing coil. The optical head is adjustably positioned in the tracking direction crossing with respect to the focusing direction, by the electromagnetic force generated when applying the electric current to the tracking coils. There may be a focusing error when the light is projected from a light source, incident on the object lens, and focused on the surface of the optical disk. Because the optical head is minutely controlled by the driving method as described above, the focusing error generated from the focused optical signal can be minimized.
The conventional optical pickup having the construction as described above, however, has shortcomings as follows. First, because the electric current should be continuously applied to the focusing coil to move the optical head, power is considerably consumed. Second, because a distance between the optical disk and the lens, which is adjustable by the electromagnetic force, is approximately 1 mm, it is difficult to apply the conventional optical pickup to a drive requiring a distance of several hundred nm, such as a far field or a near field drive having a high density. Third, because it is difficult to avoid a repeated collision between the object lens and the optical disk by external or internal shock, the optical pickup is considerably damaged by shock. Fourth, because a distance between the optical disk and the object lens is of several hundred nm, the disk and the head are easily damaged due to collision incurred while mounting or removing a disk cartridge with the disk on or from the drive, or loading the optical head section.
Accordingly, it is required for the optical pickup to adjust the distance between the optical disk and the lens to be of several hundred nm, and to maintain stability from external shock or the collision.